The structure and function of ciliated epithelium were studied in 44 human nasal mucosa samples using a photoelectric method and scanning electron microscopy (SEM). The ciliary beat frequency (CBF) of cases with recurrent or chronic sinusitis was 9.1 +/- 5.4 Hz. In eight of the samples (18.2%) no ciliary activity was detected. The amount of ciliated cells, the orientation of cilia, epithelial metaplasia, and secretion were found to be explanatory factors accounting for the decreased ciliary activity. Ciliary disorientation and a lack of ciliated cells in SEM correlated with low ciliary activity. In cases where sinusitis secretion was not seen, the CBF was slower than in cases with mucus or mucopurulent secretion. Sinusitis with disoriented cilia, a loss of ciliated cells, and a lack of mucosal secretion is associated with a decreased CBF. This may lead to impaired mucociliary clearance and increase the risk of recurrent and chronic sinusitis.
1. The ciliary beat frequency (CBF) of six animal species from six regions of the respiratory tract were measured: inferior turbinate, nasopharynx, the upper part of trachea from first to second cartilage, the lower part of trachea, main bronchus and subsegmental bronchi. Cow, pig, dog, rabbit, guinea-pig and rat were studied. 2. There were no significant differences in the CBF values between cow, pig and dog, and the ciliary activity was essentially the same (11.3-16.9 Hz) in all parts of the respiratory tract. 3. In the rat, the CBF was slower, especially in subsegmental bronchi (6.8 Hz). 4. In general, CBF was higher in upper than lower airways, with the exception of guinea-pig. 5. Signal quality was the highest in guinea-pig tissue, whereas rat tissue produced the signal with the widest variation in CBF and the highest proportion of distorted waveforms. 6. Therefore, for studying drug effects on ciliary activity, guinea-pig seems to be a more suitable animal than the more commonly used rabbit or rat. In drug comparisons, the same part of the respiratory tract and the same animal species should be used.
Many preservatives commonly included in nasal drops and sprays are known to impair mucociliary clearance. We studied the effects of four frequently used preservatives on ciliary beat frequency (CBF) in respiratory tissue. Sodium metabisulfite and chlorbutol did not change the CBF at concentrations up to 50 mg/L in rat tracheal mucosa. Chlorocresol 25 mg/L and 50 mg/mL reversibly decreased CBF (by 33% and 68%, respectively) in 60 minutes. Benzalkonium chloride impaired CBF irreversibly already at a relatively low concentration (12.5 mg/L). To further clarify these results, we studied the effects of the most ciliotoxic (benzalkonium chloride) and nonciliotoxic (chlorbutol) preservative on guinea pig tracheal epithelium and human nasal mucosa. Although chlorbutol had no effect on the CBF, a dose-dependent decrease on CBF was seen in guinea pig and human ciliated epithelium during their immersion in benzalkonium chloride. At a concentration of 50 mg/L it stopped the ciliary activity in 40 minutes in guinea pig trachea, and in human nasal mucosa, benzalkonium chloride concentrations of 25 and 50 mg/L, decreased the CBF irreversibly (by 28% and 60%, respectively) in 60 minutes. These results suggest that chlorbutol is a safe and well tolerated preservative. Banzalkonium chloride is ciliostatic in vitro to rat, guinea pig, and human respiratory mucosa. Therefore, prolonged clinical use of benzalkonium chloride may impair mucociliary clearance, a major defense respiratory mechanism.
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